This invention relates to a gas turbine combustion chamber with combustion chamber tiles, in which the combustion chamber tiles are attached to a supporting structure of the gas turbine combustion chamber, each tile possessing at least one dilution air hole which is flush with a dilution air hole of the supporting structure.
As is known from the state of state of the art, tiles are used on gas turbine combustion chambers to protect the supporting and sealing structure against the intense heat irradiation of the flame. Thus, the supporting structure is kept relatively cool and retains its mechanical strength. Accordingly, dilution air must be passed from the outside from an annulus through a dilution air hole in the supporting structure and through a dilution air hole in the combustion chamber tile to the inside into the combustion chamber.
Such designs are known from Specifications U.S. Pat. No. 6,145,319 or EP 972 992 A2, for example.
In the designs according to the state of the art, the diameter of the dilution air hole of the supporting structure (tile carrier) is maximally slightly larger than the diameter of the dilution air hole of the combustion chamber tile. In the state of the art, the only purpose of this dimensional difference is to ensure that the rim of the dilution air hole of the supporting structure does not protrude beyond the rim of the dilution air hole of the combustion chamber tile under the most adverse combination of all manufacturing and assembly tolerances.
If a gap occurs between the tile rim and the supporting structure in operation, quite a considerable amount of cooling air will leak through this gap due to the large pressure difference between the tile interior and the dilution air hole.
In order to avoid premature failure of the combustion chamber tile by the resultant overheating, the amount of cooling air through the combustion chamber tile must be increased significantly. Accordingly, this additional cooling air is no longer available for improving fuel preparation and the associated reduction of nitrogen oxide emission.